Quote:
Originally Posted by FRANKIDOWNUNDER
The figures I gave are from the Jeep manual. My ZG has the same engine as the XJ, 4Ltr 6 cyl. With 243000 Km on the clock my hot oil pressure readings are 3.5bar idle and 4.3 Bar at 2000 Rpm (using 14.2psi = 1 Bar). I use HPR 10 (10W 50) full synthetic oil and aRyco Z89 filter. I mention this because oil viscosity and /or poor filter can affect oil pressure readings. Usually a stuck pressure relief valve will cause very high pressure at startup with cold oil, pressure can be in excess of 120 psi. this would likely cause your filter to burst or distort. When the engine is hot the relief valve is usually fully closed so as to maintain sufficient pressure. Most oil pump problems are due to wear causing too low an oil pressure. If your oil pressure is within the manufacturers limits I would leave well alone and not touch the oil pump. The variation between old and new sender units could be explained by resistance variation inside the unit, as they age so the resistance changes this is why it is important to check the actual pressure using a master gauge. According to the Chrysler manual the relief valve is not adjustable so it may also not be repairable, does anyone know for sure?.
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Does anyone know if the relief valve is repairable? Or do I have to get a new oil pump? From Franki's comments, I think this is the problem I have. My oil light seems to come on in the morning, but once the engine has heated up the oil light goes away. It also seems to go off if I change up a gear and lower the RPMs. I use fully synthetic oil and the no cheap filters. I changed the sender and the problem went away for a week or so, but now it's back again. The master gauge shows oil pressures within normal levels. I have ordered an electric oil pressure gauge to mount internally which may help with diagnosis, but obviously won't help until I receive and install it. The ECU came up with 2 logs when I went to the mechanic on Tuesday - one low pressure and one high pressure; and I think the low pressure may have been when I changed the oil sender. The oil light came on again pretty much as soon as I left the mechanic on Tuesday on a cold engine, but as normal, the engine warmed up and it went away. I'm going back to the mechanic tomorrow to see what the ECU logs are this time, but I'm thinking it will show high pressure only as I haven't touched the oil sender.
Anyway - does anyone know if the relief valve it repairable?!
I have a 2007 JK Wrangler CRD by the way but I assume the problem would be similar.
I'll let you know the result when I get to the bottom of it.